Disposable training pants are well known and several different designs are available. For example, disposable training pants having front and rear portions fixedly attached together are known from WO-A-95/29657 and WO-96/31178. These designs provide adjustability of the waistband size to a range of users due to various elastic arrangements, but they must be removed like a normal pair of pants since the waist regions are formed with substantially continuous waistbands.
WO-A-00/35396 also discloses training pants with side panels which can be elastic. The side panels are formed overlapped and attached together in a prefastened state by means of releasable fastening means. The side closures further include an adhesive between them, in order to limit accessibility to the reclosable fastening means. The adhesive is placed so as to connect the outer flap of the overlapped flaps to the inner flap at a distal end location of the outer flap beyond the location of the releasable fastening means thereon. This provides a child-safety function. The adhesive bond is then opened to gain access to the reclosure element. Since the adhesive must allow access to the reclosure means without destruction of the side panels during opening of the adhesive bond (otherwise the product would be ruined) a low bond force must be used for the adhesive. In preferred embodiments the glue should remain tacky to allow repeated opening and reclosure.
GB-A-2 267 024 discloses a prefastened absorbent product providing the possibility of rupture of the side seams for removal or inspection of the product, and then the further possibility of re-closure. The absorbent garment has a rear portion, a front portion and a crotch portion therebetween, in which the rear portion and the front portion are united together by a seam. The seam is constituted by a line of attachment passing through the outer edges of the front and rear portions at each side of the garment. To allow opening of the article by tearing, the front portion is provided with a line of weakening at either side, at a location spaced inwardly from the seam. Also, a re-closure possibility (i.e. releasable fastening means) is provided by two additional side panels on the front portion. A first edge of each of the side panels is fixedly attached to the outside of the front portion in the same seam as used for the rear and front portions, and a second edge of each side panel is provided with releasable attachment means which can releasably attach to the front portion.
GB-A-2 267 024 presents several disadvantages. Firstly, in order to prevent the front and rear portions of the diaper from separating involuntarily due to the forces arising due to the wearer's movement which act directly on the seams from inside the product, the seam has to be made particularly strong. Bonding using a force of 1000 g/inch (393.7 g/cm) or more is thus required. At the same time, the line of weakening in each of the front portions has to possess a force of rupture below the bonding force level in the side seams, to avoid the seam being pulled apart when opening the diaper, yet still sufficiently high to prevent the line of weakening from being ruptured involuntarily.
The balance between these forces is difficult to achieve reliably, especially in high-speed production, particularly since the seam has to extend through three layers of material. Producing a reliable seam extending through all three separate layers of the product adds a further difficulty to be taken into account when producing the required bond strength.
Still further, the releasable attachment means on the front portion side flaps is releasably attached to the front portion of the product with a strength which should prevent the product from coming apart involuntarily when only the front portion side flaps are used to hold the product together. Due to this arrangement, when the front portion is to be pulled away from the rear portion at the lines of weakening, the releasable attachment means will exert a force on their line of attachment in the seam unless the reclosable means is first undone. This force may rupture the seam between either the front and rear portions or the front portion and the front side flaps.
A further known solution using a flush and welded connection between two side portions of a diaper is disclosed in U.S. Pat. No. 5,370,634. The flush seal is subject to peel forces arising from the normal movements of the wearer. Likewise the sealed area presents outwardly extending edge portions which are sealed at their outermost edges, thereby producing relatively hard combined edge portions. This is not only unsightly, but the hard free edge can easily come into contact with the user's skin at the upper and or lower edges thereof, causing discomfort.
The seam produced in GB-A-2 267 024 also has further disadvantages in that not only two, but three panels are combined with their outer cut edges lying outside the seam. As in U.S. Pat. No. 5,370,634, this produces a stiff edge arrangement, since the seam lies just inside the edges of the three panels. This again can affect comfort when the wearer's clothes press against the hard seam edge for example, as well as resulting in discomfort at the upper and lower edges of same. The flush seams in both U.S. Pat. No. 5,370,634 and GB-A-2 267 024 nevertheless allow production in a flattened condition.
WO-A-99/65438 discloses a further garment arrangement in which the outer edges of a front waist section are overlapped by two rear side panels of a rear waist portion. The outer ends of the front waist portion are fixedly attached by means of passive bonds to the inner surface of the rear waist portion and to the leg elastic at the rear part of the garment. The rear side panels further comprise two different type of reclosure means in the form of hook and loop fasteners which are releasably secured to the front waist portion. In this way, the passive bonds provide added shear strength to assist the reclosure means. Such an arrangement can provide a stable side closure system as a result of the passive bond locations. However such products suffer from a lack of adaptability and poor comfort and must rely on the waist band to provide some limited elasticity.
The invention has the object of providing an absorbent product with an improved side closure construction which allows low attachment forces to be used in releasable and non-releasable (i.e. fixed) attachment areas, while maintaining a closure arrangement which is reliable yet which allows a high degree of elasticity in the side closure and at the same time providing a good fit on the wearer.
The present invention also seeks to provide a method for producing an absorbent article of the type described above which obviates the problems with a flush seam and yet which can be easily formed in a flat condition during production.